Non-woven Separation Fabrics
Non-woven geotextile fabrics are generally used for reinforcement, separation, filtration, and erosion control. These fabrics are durable on a varying scale with the heavier fabrics being the most resilient to tearing. Polypropylene staple fibers combine high water flow rates which are an ideal material choice for use in various drainage applications. Aside from drainage, non-woven fabrics can also be used as an underlayment in road stabilization.
When used in drainage applications non-woven geotextiles offer excellent filtration characteristics and prevent dirt and aggregate from clogging up drainage systems which can help to extend the system’s life and increase its performance.
Other applications include under walkways, patios, landscape, water features, under riprap to redirect excess water, erosion control, retaining walls, and shoreline protection. Thinner fabrics (lighter weight) fabrics are typically used for drainage while the thicker fabrics are most often installed in erosion control or stabilization scenarios. The GEOTEX 401 is on the lighter side and is perfectly suited for general drainage applications. Be sure to consult with an engineer or landscape architect on the most appropriately weighted fabric for your specific application.
Nonwoven geotextiles are made using a synthetic textile. That said, they have a more random structure that's produced by the interlocking fibers. Woven and nonwoven are used in similar ways which can be somewhat confusing. The easiest way to show the difference between the two is by their physical attributes. Nonwoven geotextiles look and feel like felt with a fuzzy look to the material.
To manufacture nonwoven geotextiles today, there are many different methods. The most popular method is needle-punching. Needle-punched nonwoven geotextiles are made by taking a large number of small fibers and using a barbed needle to interlock the fibers together. Nonwoven geotextiles are mostly used for separation combined with filtration and drainage capabilities when used for civil applications.
The difference between woven and nonwoven geotextiles can be difficult to determine when looking at the material specifications. In general, woven geotextile has higher strength values, while nonwoven has higher flow rates and permittivity. The best way to distinguish the difference between the two is by starting with elongation. Nonwoven has a higher elongation than woven. A nonwoven specification lists the elongation as being greater than 50% while woven is only between 5 to 25%.
As there are significant differences between their elongation and permittivity, tensile strengths are pretty similar given they are both manufactured from similar materials. All of this is important in order to choose the correct kind of geotextile for your project. It's important to make sure you choose the right product for your specific reasons.
The Weight of Nonwoven Geotextiles
Another important difference between the two geotextiles is the weight. The weight of a woven geotextile is hardly ever mentioned. The reason is, that they are typically used for separation and reinforcement and therefore are not reliant on weight.
On the opposite side of the scale, the weight of a nonwoven geotextile is often specified. Consumers will say they want an 8 oz or 10 oz box. For a long time, nonwoven geotextiles have been measured by weight, meaning the finished product would be 8 oz per square yard. The other specifications include strength, puncture, etc which is still a direct result of the product's weight.
With the continual popularity of geotextiles, its growth and development have influenced the manufacturing process which has changed as well. Most nonwoven geotextiles can be made with a lighter weight and still achieve the same strength properties which have led to reduced costs. There are always some exceptions including using nonwoven as cushion geotextiles underneath geomembranes. In cases like this, puncture, weight, and thickness are more important than permittivity and strength.